1. Field of the Invention
The subject of the present invention is a novel seal for the surround of an opening in motor vehicle bodywork, particularly for the surround of a door, trunk, tailgate, window, quarterlight, or the like.
Such seals for surrounds of openings in motor vehicles generally comprise:                a section piece forming a clip with a U-shaped cross section, made of elastomer or of plastomer, usually comprising a rigid armature and intended to fit over and clip onto part of the surround of the opening in the motor vehicle bodywork;        and at least one tubular section piece made of an elastically deformable material, generally a cellular material, abutting, for example, a lateral branch or the base of the U-shaped section piece and projecting toward the outside from the surround of the opening, with a view to being compressed between the opening leaf and this surround, when the opening leaf is in the closed position, so as to seal the vehicle.        
The U-shaped section piece and the tubular section piece are customarily made of thermoplastic or elastomeric materials and are produced by coextrusion.
Aside from its sealing role, when compressed by the opening leaf when the latter is in the closed position, the tubular section piece also has a function of soundproofing the cabin of the vehicle.
2. Discussion of the Prior Art
Numerous forms of embodiment of such seals are known in the state of the art and all are generally aimed at providing excellent soundproofing, without detracting too greatly from the ability of the tubular section piece to deform.
In their French patent application No. 00/04414, filed on Mar. 31, 2000 and not yet published at the date of filing of this application, the applicant company proposed a seal of the same general type as those mentioned hereinabove but which, unlike those of the prior art, which were aimed at having excellent ability to deform, locally put up increased resistance to the compression by the opening leaf when the latter was closed.
Specifically, when motor vehicle doors are highly curved, they tend to deform as the vehicle runs along at high speed, under the effect of an external depression, and it is important to be able to oppose this deformation. With a seal which puts up greater resistance to the closing of the doors, these doors, having been closed, are preloaded, which allows them better to resist the external stresses when the vehicle is moving along at high speed.
Furthermore, with certain vehicle trunks, it is sometimes necessary that, when closing the opening leaf, the trunk seal should at least locally put up sufficient resistance to this to act as an end-of-travel damper, thus avoiding vibration occurring later.
In order to meet these requirements, the applicant company, in the aforementioned patent application, proposed a seal for the surround of an opening in motor vehicle bodywork, this seal comprising a first section piece forming a clip of U-shaped cross section, made of elastomer or of plastomer, capable of sitting over and gripping a projecting part of the surround of the opening, and a second section piece of U-shaped cross section, made of an elastically deformable material, arranged to the side of the first section piece, with the ends of its branches abutting one of the flanges or the base of this first section piece, so as to form, with this flange, a tubular member, this second section piece comprising at least one orifice placing the inside of the section piece in communication with the outside and being intended to be compressed elastically via the opening leaf associated with the opening in the bodywork, when this opening leaf is in the closed position, so as to seal at the surround, this seal being characterized in that, housed inside the second section piece and along at least part of its length, is a third section piece with a U-shaped cross section, which is smaller in size than the second section piece and the ends of the branches of which also abut the same flange or the base of the first section piece, this third section piece also being made of an elastically deformable material and intended to put up local resistance to the compressive force exerted by the opening leaf, while at the same time improving the sealing and soundproofing at the surround of the opening.
Like the second section piece, the third section piece of this seal may be pierced with at least one orifice placing the inside of the section piece in communication with its outside. It may also have no such orifice, for certain applications of the seal.
The third section piece of this seal of the prior art therefore has a three-fold function:                to put up greater resistance to the closing of the opening leaf;        to act as an end-of-travel damper for this opening leaf when the latter reaches its closed position;        to oppose the passage of soundwaves and thus better soundproof the cabin of the vehicle, when compressed by the opening leaf.        